Puppy instructions
Download file by clicking on it
Open the Puppy package manager. (under setup by default)
'Click button to run the PETget package manager'
Choose the second icon down (install binary)
Locate the file and click ok
Follow the prompts

NOTE:
I noticed that MonkeyMenu is not compatible (already fixed - see the italic statements below) with extensions like StumbleUpon that add toolbars. When MonkeyMenu over-writes the Seamonkey UI it improves it a lot by adding many features but at this time 2/2007 it can't see other toolbar type extensions so if you use Stumbleupon or other add-ons that add toolbars you should test how you like it with a live cd.

"...add about 28 buttons to the Seamonkey user interface, collapse any toolbar, add/remove search engines, have your font zoom size reloaded, and use the new Search box feature. Basically the extension revamps the browser UI making it easier and faster to use."

I'm running them now in Puppy 2.13 and they work perfectly for me.

There is also a link to an experimental extension installer/uninstaller.
Be careful using this as it may mess up Seamonkey.

I am Mark Bokil, the developer of MonkeyMenu, SeaFox and SeaGnome. I saw on this that it says that Monkeymenu does not work with Stumbleupon and other toolbar extensions. This was fixed in the last version of MonkeyMenu and all toolbars work as expected.